Zenitsu Agatsuma is a character in Kimetsu no Yaiba.
He was a demon slayer like the protagonist Tanjiro.
He, together with Tanjiro and other companions, took part in the Final Selection of Demon Slayer and fought together. And he is one of the five survives.
He has short hair with uneven bangs, thick hanging eyebrows split in two at the end of the eyebrow, the dark circles around the eyes give a melancholic impression. At first glance, he has exquisite features, but according to his personality described later, he can only be seen in the state of making faces in most cases.
The details will be mentioned later. However, when he first appeared, his eyes were a little sharp and his body was a bit dirty, and he seemed to be an experienced swordsman. However, according to the animation version of "Taisho KotsuKotsu Gossip", it made clear that he was reluctant to participate in the final selection and he was forced to take part in it by his mentor.

He was born with black hair, but he was hit by lightning during his practice. Therefore, his hair turned into blond.
By the way, the accent of his name is pronounced flat (It is similar to "Enpitsu").

We can describe him as" stupid boy "and " pleasant to the eye but of no use ".
Because of the contrast between his timid personality and his aptitude and ability which was introduced in later volumes, he has gained great popularity among some readers. He ranked second in the first official vote of popularity which is held by JUMP in 2017 (His hand should have been written a message to the readers, but it was actually some resentful words to Tanjiro.)

Character

He is a coward and womanizer who is always noisy.

His behavior often appears strange due to his extreme timidity and prudence. He cried with tears and snot at will, shouted "I’m afraid of demons" and "I don't want to die".
Tanjiro who is well-behaved thinks that he has a melancholy and dejected face, and even the children look at him with contempt, which makes him quite distressed. After arduous training and rigorous selection, he should have the physical ability as a demon slayer, however, it doesn’t show. It can be seen from the above description that "I will die." is his pet phrase. Even if he passed the final election, he repeatedly said "I will die in the end"He often said some pessimistic words, such as "I will die soon! Next job! “I am doomed to die, and so on.”
He is also not confident when carrying out task. When facing demons, he not only has to run away with all his strength, but also because of his excessive fear, he cannot walk normally.

Zenitsu has no resistance to beautiful women. He is a typical womanizer. He became a demon slayer because the cultivator, who cultivated and trained demon slayers, helped him to pay off debt which belonged to the woman who cheated him. (the woman let him bear her debt, and then she eloped with other man). When he met with Tanjiro again, he feared death as usual when facing task. He would keep pestering girls he didn't know and force them to marry him with crying and shouting.
When he first met the heroine Nezuko, although he knew that she was a demon, he fell in love with her for her beauty at first sight. Therefore, he obviously showed modesty and humility to Tanjiro, and he is always frank and honest with himself.
Although he is very timid, he is dauntless and straightforward when facing his own desire. During Rehabilitation Training in Butterfly Estate, when Tanjiro and Inosuke provided him a very painful massage, he said that you should smile and enjoy the massage when girls do this for you, (Inosuke said that "he is not an ordinary person").. He is very jealous of Hashira, who ordinary demon slayers would feel the intimidating pressure when they just get close to him, therefore, he often gets angry with him and contradicts him. He has a strong self-awareness. In a way, he is a big man.
Basically, he has affection for all girls, but he is not good at dealing with girls like Aoi, who is a hot-tempered class monitor.

A kind and gentle person by nature.

He is upright and kind-hearted. Although he was nervous and afraid in the face of demon, he will immediately protect children. He will say that you guys run first without hesitation.
Because his sense of hearing is extremely excellent, he can tell other people's lies just by listening to their voice. However, he is a person who only believes people who he wants to believe. He was enslaved by seven women before he was saved by the cultivator. His money was robbed. There is nothing he can do about it. He is often cheated by others. He knew that Tanjiro was protecting a demon, and he had faith in the gentleness of Tanjiro. Even if he was assaulted by Inosuke without resistance, he also protected the box in which Nezuko slept.

Outside the battle field, Tanjiro gave the rice balls to him for he was hungry. When he knew that there was only one rice ball, he returned half of the rice ball to Tanjiro.
He has a great affection for Nezuko in the very core of his heart, and he will subconsciously stand up to protect her. His thoughts are so real.

Basically, he always carried out the task unwillingly while crying. Even during the treatment, he would not be quiet. However, he seemed to grow mentally every time when he finished the task. When he first met Sound Hashira, he was intimidated by his imposing appearance. Tanjiro and Inosuke managed to calm outrageous Zenitsu who was forced by Aoi Kanzaki to carry out the task. When met Upper Moon Demon in the beginning, even though he was frightened by her momentum, he still managed to protect injured son of a prostitute, and finally he was blown away. He began to realize his responsibility of being a member of the Demon Slayer Corps.

In addition, Tanjiro was born in the countryside and kept pure and naive, and Inosuke was raised by boars in the mountain, as the only one who born in the city among the three, Zenitsu knew more about this world. He therefore undertook the preparation of train tickets and other things concerning tasks.
However, what he likes is also based on this standard. He is fond of eel, sweets, premium foods and high-calorie foods. If he is not a demon slayer, he may become obese.

His heart is covered with cloud of melancholy

In fact, he was an outcast and was abandoned by his parents before he got a name.
When he was trapped in nightmares created by Enmu, he was surrounded by darkness. Perhaps it was because the one who invaded was a man, the ‘Zenitsu who hates gloomy men’ inside his heart was drawn out and he attacked the intruder with big scissors.

If you look carefully at the plot mentioned earlier, he can clearly distinguish the lies, but he chooses to believe what he wants to believe. He also has many shortcomings. When he sees the troubled and disappointed Inosuke, he laughs at him. If he sees the part of female body, he cannot help but touch it. In addition, he is always mentally unstable every time he performs a task.

In the past, he was beaten by his mentor and his fellow members during his training. His training didn't go on well, then he tried to run away but didn’t succeed. Finally, he learned a technique that will be broadcast in the official release.
He didn't kill any demon, instead, his companions and even some people who didn't train became able to kill demons. No wonder he became even less confident and he just wanted to fall asleep.
Please help him! He couldn't believe his strength.

Ability

At first glance, he seems to have no fighting ability, but he began to find his extraordinary ability after the teaching and guidance by the former Hashira. After hard training, he made strenuous efforts to pass the final selection.

As a demon slayer who should protect the weak, Zenitsu feels very nervous and horrified when he has to kill the demons, he would fall asleep like lost the soul.

――Only when he is sleeping can he display his true strength.

He does not show his fighting ability at ordinary times because fear makes his body stiff and unable to move. Sleeping can make all sinister feelings that hinder him disappear, allowing him to exert his original physical ability.

He can cut off demons’ bodies instantly as quickly as a flash of lightning. Let alone the action of drawing the sword, even the action of putting the sword into its sheath cannot be carefully observed.

Of course, because Zenitsu battled in sleep unconsciously, he never dreamed that he would kill demons. After battle, he woke up discovering the sword in the scabbard and the rolling demon head beside him, he felt very strange and confused.

Sense of Hearing

Tanjiro is excellent in sense of smell while Zenitsu has a very excellent sense of hearing.
Sleep state = He can engage in battle even with his eyes closed because his sense of hearing is so excellent that he doesn't need to see.
Based on his sense of hearing, he can correctly and quickly observe the situation around him, and distinguish the unique sound made by demons. If there is a demon in the crowd or hiding in the box, as long as it is within a certain range, he can employ extensive and powerful searching ability.
In addition, he can read the other party's personality and psychological state through their voice. Because of the combination of espionage and perfect pitch, his sense of hearing can be widely used, such as copying music through his ears.

If only his advantages are listed, he seems to be able to play a very high ability of information collection in his daily life. However, due to weakness of personalities, such as timidity, panic, and being unable to observe others' mood, he can't handle interpersonal relationship well and deal with difficulties and troubles in his daily life.
Because of these things, he was given the title of "man who only plays a role in the critical moment" by his fans. It is unknown that whether this title is a praise him or derogation of him.
By the way, the other two people in Kamaboko Team are tone deaf. On the contrary, Zenitsu has perfect pitch and is good at playing musical instruments. When Tanjiro painted an ugly painting of a human face fish to teach Inosuke carp streamer, the carp streamer painted by Zenitsu was very vivid and lifelike like the real monster, he is the most artistically gifted of the three.

Physical ability

The physical ability of the selected demon slayers after training is superior to that of ordinary people, and they can instantly improve their physical abilities to battle against demons through "Full Focus Breath" mentioned later.
However, as described above for Zenitsu, when facing the enemy, he fails to fully exert his ability due to his nervousness and fear.
But in the usual training, his basic ability is very solid, and he has the same movement speed as other teammates like Tanjiro. In terms of speed (including reflex nerve and motion object vision),he has very excellent performance(In fact, he is the first one to pass the reflex training in Butterfly Estate>Shinobu Kocho]]).

Full Focus Breath can significantly strengthen the heart and lungs of human and allow them to absorb large amounts of oxygen into the blood at one time and instantly enhance their physical ability that is equal to demons. This is a technique that enables human to battle against demons and even kill them.

Here is the technique of "Breath of Thunder" employed unconsciously by Zenitsu.

Originally, there are six styles in Breath of Thunder. However, Zenitsu only learned First Style mentioned below, he is incapable of employing other styles.
However, he refined the technique to the limit and upgraded it to more unique development technique. As a result, he defeated all opponents who employed the same technique, belittled him and challenged him.

First Style Thunderclap Flash（Hekireki Issen）

This is the only style that Zenitsu can employ among all basic styles of Breath of Thunder.
He jumps off employing God Speed with the flash of iaido.He is so fast that even demon can't capture his movement, let alone humans.
Zenitsu devoted all his intelligence and training to the research of this technique, and eventually became famous for the power of slaying sword and his fast speed like a lightning.

First Style Thunderclap Flash Six Fold （Hekireki Issen Rokuren）

Zenitsu has only learned the thunderclap flash of the straight track, he has found out the answer by himself in order to eliminate the demon.

He has the ability to send out a flash six times in a row, and engages in attack which is beyond the recognition of demons. Moreover, he is capable of attacking multiple objects at the same time.

The sound of impact of jump caused by super speed combo is generated for six times. Demons, whose sense of hearing is superior to human, can only hear one sound which consists of six sounds. That sound vibrates the tympanic membrane like thunder.

First Style Thunderclap Flash Eight Fold（Hekireki Issen Hachiren）

After his, mission in Mugen Train, he learned this technique through strict special training.
After knowing the tenacious life of passion that keeps fighting until the end, in the face of the one that far beyond human’s reach, Zenitsu creates this technique in order to enhance himself.
He is far from achieving his goal. Therefore, he has to take new steps and keep moving forward.

First Style Thunderclap Flash God Speed（Hekireki Issen Shinsoku）

Trump card of Zenitsu
By employing God Speed, No one can touch him or even one of his feet cannot be touched.
His god speed combines with the flash of his sword (the contact time of his sword is extended in unit time), and the power of the sword is greatly enhanced.
At the same time, because the super speed movement can generate very large energy, which allows him to escape from the constraint.
However, it will impose a great burden on Zenitsu's body, and he can only use it twice at a time.
In particular, the damage of this technique to the foot is beyond imagination. After using it twice, his foot will have severe fracture and obvious deformation.
If he doesn't kill the demon with this technique, he will die.

This is basically the same as Thunderclap Flash. He jumped out of the air and then released a hit. However, he tilted his body forward and waved the sword, which resembled a thunder dragon.
His speed is faster than God Speed, which is beyond the opponent's recognition, and he waved his sword to chop as he moved forward.
The whine of his sword disappeared in the thunder. The phantom was the God of Thunder.

Equipments

Demon Slayers are equipped with the Nichirin Sword and team uniform. In addition, Sparrow is assigned to members for communicating tasks and conducting supervision.

The Nichirin Sword

Because immortal demons can only be killed by the sun, so this knife is the only weapon that can cut off their heads and kill them. Please refer to here for details.
The Nichirin Sword of Zenitsu is "yellow". The edge of the sword is painted with colored patterns like lightning.
Moreover, the color of The Nichirin Sword indicates that he has the ability to reach the highest level of Breath of Thunder.

Team uniform

The team uniform is black Gakuran with a word ‘SLAY’ on its back.
The uniforms are made of special fibers, this uniform have good air permeability and are waterproof and fireproof. In addition, the uniform was so strong that the demon's claws and fangs could not tear it apart.

Sparrow

Usually, each team members of Demon Slaying Corps would be assigned with a crow which can understand human language and speak. However, it is unknown why only Zenitsu is assigned with sparrow.
Please refer to "Chuntaro" for details.

Nonsense Collection（A part）

"Ah! Why are you broken, my bones? How could my bones break? If you were broken Tanjiro cannot protect me and I will die! "

"Signal, give me a signal. If you want to talk to me, please don't hurry, my heart will jump out of my mouth. If that's the case, you're a murderer!! Do you understand!? "

"Ah… (dirty high-tone voice) Don't come! Don't come! Stop…! "

"Ah! Ah!! It's on my knee. I'm so scared! "

"You apologize! You must apologize!!! Don't put on a face like hell in heaven!! Obviously, you just quarreled with girls every day, and you unexpectedly appear haggard, you should kneel down to apologize and commit harakiri"

"Every girl has two boobs, two buttocks and two thighs. If they pass me by, I can smell their fragrance. I am happy to watch them!"

" I will get you back! I will definitely become the number one Oiran in Yoshiwara! "※ No way

Collection of Quotations（On the brink of extermination）

"I ... will ask Tanjiro directly, so you ... get out of here!!"

"No matter how strong a person is, there will always be times of pain and sorrow, but it's useless to be depressed all the time, and you should forget the sadness and cheer up again."

"But I'm really happy to be able to do things I couldn't do before. Tanjiro has been encouraging me. He's a really good brother, Nezuko."

"I will protect Nezuko!''

"I want to say something to you. Listen to me. Apologize to the injured child."

"If I'm a scum, then you are rubbish. I can only employ First Style and you only cannot employ First Style. It's pathetic that that old man has no perfect successor. "

Digression

Combat Style
He usually wears Gakuran with a scabbard in the belt around his waist， which is convenient for him to perform iaido. When performing task in Yoshiwara, he wore the clothes without belt, so he took the Zatoichi style that he held the scabbard in his left hand.
By the way, The Nichirin Sword is often broken or lost in the battle against demons in Demon Slayer Corps, which can be said to be a consumable. In fact, Tanjiro' sword has been damaged three times in the animation. Even Inosuke lost his sword once. However, it can be seen from the description of the animation that only Zenitsu's sword has not been broken or lost.
Taking these things into consideration, some readers think that Zenitsu is the strongest among his contemporaries.

Character Voice
When choosing the voice actor for Zenitsu, Hiro Shimono is voted the most suitable for Zenitsu’s dirty high-tone voice and became the champion.
Mr. Hiro Shimono, do your best as the champion of dirty high-tone voice, please!

Popularity Voting and Sister Krone
When he officially appeared in Episode 20, the collaborative portrait of him and Sister Krone of "The Promised Neverland" became very popular on the Internet. Perhaps for this reason, she ranked 29th in the popularity voting of "The Promised Neverland" (She got 44 votes). Perhaps the offical has noticed this too. Sister Krone is being roasted. Sister krone, by the way, ranked 59th in the popularity voting of Kimetsu no Yaiba (She got 4 votes).
In other works, Samon-kun wa Summoner, she also obtained 3 votes in the popularity voting.